The Liquid Crystal Display (LCD) possesses advantages of thin body, power saving and no radiation to be widely used in many application scope. It has been widely utilized in, such as mobile phones, PDAs (personal digital assistance), digital cameras, laptop screens or notebook screens.
Generally, the liquid crystal display comprises a shell, a LCD panel located in the shell and a backlight module located in the shell. Particularly, the structure of the liquid crystal panel mainly comprise a TFT Array Substrate (Thin Film Transistor Array Substrate), a CF (Color Filter) and a Liquid Crystal Layer. The working principle is that the light of backlight module is reflected to generate images by applying driving voltages to the two glass substrate for controlling the rotations of the liquid crystal molecules.
The COA (Color-filter on Array) technology is an integration skill of directly manufacturing the color filter on the array substrate. It can effectively solve the issue of light leakage caused by the misalignment of the liquid crystal display device in the cell process and can significantly raise the display aperture ratio.
Please refer to FIG. 1 and FIG. 2 which shows a COA type liquid crystal display panel according to prior art, comprising a lower substrate 100, an upper substrate 200 oppositely located to the lower substrate 100 and a liquid crystal layer (not shown) located between the lower substrate 100 and the upper substrate 200;
the lower substrate 100 comprises a plurality of pixel units, and the pixel unit comprises a first substrate 110, a common electrode line 120 and a gate scan line 130 located on the first substrate 110, and an insulation layer 140 located on the common electrode line 120 and the gate scan line 130, a color resist layer 150 located on the insulation layer 140, a passivation layer 160 located on the color resist layer 150 and a pixel electrode 170 located on the passivation layer 160;
the pixel electrode 170 comprises a frame electrode 175 located at peripheric edges, and a storage capacitor Cst is formed between the frame electrode 175 and the common electrode line 120 located below correspondingly thereto;
However, in the lower substrate 200 of the COA type liquid crystal display panel according to prior art, the color resist layer 150 continues to extend to the outer sides of the frame electrode 175, and is located between the frame electrode 175 and the common electrode line 120. Thus, the distance between the frame electrode 175 and the common electrode line 120 is increased. According to the capacitance calculation formula C=εS/d of parallel-plate capacitor (wherein ε is the dielectric constant of the medium between plates, and S is the plate area, and d is a distance between plates), the size of the capacitor is inversely proportional to the distance between the two plates of the capacitor. Therefore, the existence of the color resist layer 150 makes the distance between the frame electrode 175 and the common electrode line 120 become larger. Namely the distance between the two plates of the storage capacitor Cst is increased and the storage capacitor Cst is decreased. The requirement to the leak current in the display period cannot be satisfied, and the stability of display is reduced.